Philip K. Dick (1928-82), the reliably legendary, always eccentric, and occasionally brilliant science fiction writer whose “A Scanner Darkly” is the basis of Richard Linklater’s dreadful new movie,is often described as a philosopher, a shaman, and a seer. But that’s being kind, the man was bonkers, a nut-case, a lunatic, crazier than a street-corner shouter or attic-roosting aunt. Unfair? Maybe,but then unlike Dick I have never been fortunate enough to be “seized” by a light beam that lifted me “from the limitations of the space-time matrix” and released me “from every thrall, inner and outer.”

And if that doesn’t sound deranged to you, try popping the meds your doctor keeps talking about. Please. Just do it now.

But Dick’s madness (no small part of which was drug-fueled) defined his genius.The best of his novels play with reality, perception, time, and identity in a fun house, madhouse, crack house jumble that can inspire, infuriate, bore, and enchant. And so it’s no surprise that, after never really making the major leagues during a lifetime dominated by Asimov, Clarke, and other bards of the rocket men, Philip K. Dick has come into vogue in our own epoch of junkyard mysticism and gimcrack thought, an era where the idea of objective truth finds itself dismissed as mirage at best, deliberate deception at worst. A madman ahead of his time, Daffy Dick too was convinced that he had been “lied to.” His light beam had “denied the reality, and power, and authenticity of the world, saying, ‘This cannot exist; it cannot exist'” — asylum jabber that sounds a lot like today’s conventional, if idiotic, wisdom (and even more like a screenplay).

In the nearly quarter century since his death, eight movies (including this one) have been made from Dick’s work, generating hundreds of millions of dollars and, it sometimes seems, a similar number of bad reviews. I’ll admit to not having seen either 1995’s “Screamers” (remorseless killer machines on a distant planet) or the unpromising-sounding “Confessions of A Crap Artist” (1992), but, with the glistening, rain-streaked exception of Ridley Scott’s eerily prescient and remarkably influential “Blade Runner” (loosely based on Dick’s “Do Androids Dream of Electric Sheep?”), films such as “Impostor,” “Minority Report,” and “Paycheck” have plundered the author’s reputation but enriched his estate. As for “Total Recall,” even the presence of Arnold Schwarzenegger, a young Sharon Stone, and the most excitingly irradiated mutants this side of “Beneath the Planet of the Apes” could not stop Paul Verhoeven’s account of Dick’s “We Can Remember It For You Wholesale” from degenerating into kitsch, ham, and fiasco.

Frankly, I doubt if even the lissome Ms. Stone, the mighty Arnold, and the mutated human flotsam could have done much to salvage the wreck that is “A Scanner Darkly.” Talky, talky, talky, and with a plot “twist” so telegraphed that it could have been a Capitol Hill secret, this dreary stoner sci-fi police procedural sort-of-comedy cautionary tale (oh, call it what you want: I give up) has little future other than as an alternative for insomniacs too timid to deal with Ambien’s regrettably feeble high.

But if “A Scanner Darkly” has a redeeming feature, it is the remarkable use that Mr. Linklater has made of “rotoscoping,” something he first tried in 2001’s “Waking Life” (a beautiful movie, but more or less unwatchable, life is just a dream, whatever). Put very crudely, this is a technique by which “real action” film is overlaid with animation. Basically, the animators use the live footage as the foundation (in a sense, they trace their designs on top of it) of their own work. In “A Scanner Darkly,” the result is images that are both reassuringly realistic, yet disconcertingly skewed, a perfect way of conveying the drug-saturated milieu in which this movie’s addled protagonists stumble about their confusing, confused business (a central theme is that of a cop, Keanu Reeves, knowingly and unknowingly spying on himself). It also allows the director to portray the shifting, bewildering “scramble suits” with which the film’s undercover policemen disguise themselves, camouflage of such startling, hallucinatory loveliness that it will linger in the mind long after the rest of this wretched, interminable hundred minutes has vanished into merciful forgetfulness.

Ironically, the problem is not that Mr. Linklater has made a mess of Dick’s novel, but that he has remained too true to it. The director had already shown himself to be familiar with Dick’s thinking in “Waking Life” (which contains a number of references to the writer’s ideas), but in this movie he reveals himself to be too much a fan to tamper with a text that, if it was to make an entertaining film, needed a great deal of tampering. It may have the narrative (of sorts) and structure (of sorts) of more traditional science fiction, but Dick primarily intended “A Scanner Darkly” as a demonstration of where narcotic frolics could lead:

… this has been a novel about some people who were punished entirely too much for what they did. … we really all were very happy for a while … but it was for such a terrible brief time, and then the punishment was beyond belief: even when we could see it, we could not believe it.

With its sense of dissolving identities (reinforced by the way the rotoscoping is used to turn the film’s performers into illusions, visions, and caricatures of themselves), rambling stoner monologues, paranoia, overacting (Woody Harrelson, Robert Downey Jr., I’m talking about you two), insect visions, and insanity, this movie judders, crumbles, and ultimately tips over into being little more than a hip “Reefer Madness” hopped up with a sinister conspiracy. This is a shame, because somewhere beneath the murkily obsessive doper remorse, “A Scanner Darkly” has something important to say about the way the “war on drugs,” technological advance, and the needs of the surveillance state feed upon each other.

But that too-neglected topic will, clearly, have to wait for another movie, and the long-suffering, patient, and faithful fans of Philip K. Dick will have to return once again to “Blade Runner,” nearly 25 years old now, but possibly the greatest sci-fi movie of all time, and an extraordinary demonstration of how to translate this quirkiest of writers onto the big screen.